1. Field of the Invention
The present invention relates to a wireless terminal which comprises a reconfigurable antenna and a plurality of RF circuits.
2. Description of the Related Art
Various conventional wireless communication systems have been established, such as Global System for Mobile Communications (GSM) and Wideband Code Division Multiple Access (WCDMA). With diversification of such wireless communication systems, technical demands are rising for wireless terminals (such as mobile phones and personal computers) which support a plurality of wireless communication systems.
In order to support a plurality of wireless communication systems, an antenna which covers a broad band is required. On the other side, antennas mounted on wireless terminals are demanded to have a small size. In general, a trade-off takes place between downsizing of an antenna and band broadening of the antenna. A known solution to these two demands is a so-called reconfigurable antenna. The reconfigurable antenna is capable of substantially covering a broad band by dynamically switching limited operating bands.
Jpn. Pat. Appln. KOKAI Publication No. 2003-332938 may be introduced as an example of a technique for reconfigurable antenna. A mobile phone device described in the publication No. 2003-332938 dynamically changes a ground length on the basis of a band specific to a wireless communication system to use with. The mobile phone device described in the publication No. 2003-332938 is capable of optimizing antenna characteristics (radiation patterns at each frequency), with respect to the wireless communication system to use with.
Wireless terminals are sometimes designed such that each wireless terminal comprises a plurality of RF circuits in order to achieve switching between wireless communication systems or switching between signal transmission and reception. Usually, a wireless terminal comprising a plurality of RF circuits comprises an antenna switch for connecting an antenna selectively to the plurality of RF circuits. Based on switching between wireless communication systems or switching between signal transmission and reception, a wireless module controls the antenna switch to connect one of the plurality of RF circuits to the antenna.
The technique for reconfigurable antenna according to the publication No. 2003-332938 or any other technique for reconfigurable antenna is supposed to be applied to an antenna in a wireless terminal comprising a plurality of RF circuits. Here, a selection control for selection from a plurality of RF circuits (i.e., a control on an antenna switch), and a control of an operating frequency of a reconfigurable antenna are respectively different techniques. However, when combining and implementing both techniques together, both techniques are desirably synchronized (or linked) with each other. The related art including the publication No. 2003-332938 neither discloses nor suggests a configuration of achieving synchronization of both techniques.
The invention hence has an object of providing a wireless terminal capable of synchronizing a selection control for selection from a plurality of RF circuits and a control of an operating frequency of an antenna.